Effects of crosshead speed, infill density, and pattern type on tensile strength of FDM-printed PLA

Abstract

In this study, the effects of printing parameters and cross-head speed on the tensile test of PLA were investigated experimentally using the FDM method. The test samples printed with different printing densities (30 %, 45 %, 60 %) and different infill patterns (rectilinear, grid, honeycomb) were performed to tensile tests at different cross-head speeds (1 mm min ⁻¹ , 10 mm min ⁻¹ , 50 mm min ⁻¹ ). Additionally, printing times and material consumption were compared to calculate printing efficiency. Infill density and cross-head speed showed a positive correlation with tensile strength. According to the ANOVA statistical results, the pattern type has the greatest effect on tensile strength and post-peak fracture strain values. The highest strength values were obtained for the honeycomb, grid, and linear pattern types, respectively. The highest tensile strength was determined in 50 mm min ⁻¹ cross-head speeds, 60 % infill density, honeycomb pattern type. The highest post-peak fracture strains were obtained at a cross-head speed of 1 mm min ⁻¹ for all pattern types and infill densities. The post-peak fracture strain exhibited a decreasing trend with increasing crosshead speed. Fracture surface examination findings from SEM images revealed that the fracture occurred in a relatively ductile fracture mode at low cross-head speeds and a more brittle fracture mode at high cross-head speeds.